Door latch mechanism

ABSTRACT

A door latch mechanism having a latch element fixedly coupled to a ratchet plate, a pawl means adapted to hold the ratchet plate and thus the latch element in latched condition, a locking lever adapted to block movement of the pawl means to ratchet plate disengaged position, characterized in that the ratchet plate and locking lever are coupled to each other by a toggle spring effective to transmit ratchet plate movement to the locking lever if the latter is placed in pawl-blocking position with the latch element in unlatched condition and the latch element is moved to latched condition. The locking lever thus is normally automatically restored to pawl-nonblocking position, but the automatic restoration can be negated by at least partial actuation of an external pawl means operator which creates an interference between the pawl means and locking lever sufficient to override the force-transmitting capability of the toggle spring.

United States Patent [54] DOOR LATCH MECHANISM 2 Claims, 2 Drawing Figs.

[52] [1.8. CI 292/216 [51 Int. Cl. E05c 3/26 [50] Field of Search 292/216,

280, (J3), (J4), 19s

[56] References Cited UNITED STATES PATENTS 2,791,459 5/1957 Roethel 292/280 3,385,623 5/1968 Burns etal 292/216 Primary Examiner-Richard E. Moore Attorneys-John R. Faulkner and John J. Roethel ABSTRACT: A door latch mechanism having a latch element fixedly coupled to a ratchet plate, a pawl means adapted to hold the ratchet plate and thus the latch element in latched condition, a locking lever adapted to block movement of the pawl means to ratchet plate disengaged position, characterized in that the ratchet plate andlocking lever are coupled to each other by a toggle spring effective to transmit ratchet plate movement to the locking lever if the latter is placed in pawl-blocking position with the latch element in unlatched condition and the latch element is moved to latched condition. The locking lever thus is normally automatically restored to pawl-nonblocking position, but the automatic restoration can be negated by at least partial actuation of an external pawl means operator which creates an interference between the pawl means and locking lever sufficient to override the forcetransmitting capability of the toggle spring.

DOOR LATCH MECHANISM BACKGROUND OF THE INVENTION Thepresent invention deals with a latch mechanism particularly for motor vehicles. The latch mechanism comprises a latch plate having a bearing means joumaling a shaft at right angles to the end face of the door on which the latch mechanism is mounted. The shaft carries a latch element at one of its ends and at its other end a rachet plate, both the latch element and ratchet plate being fixed to the shaft and nonrotatable relative to one another. A pawl is pivotally mounted for movement about a pivot pin parallel to the latch element and ratchet-plate-carrying shaft. A tension spring extends between the ratchet plate and the pawl such that the two are urged in mutually opposed directions into engagement with one another. The pawl is adapted to be held out of ratchet plate engagement by means of externally and internally door mounted operating devices. Operation of the pawl and ratchet plate in disengaging direction is capable of being blocked by a locking lever operable, on the one hand, by means of a key-operated lock cylinder and, on the other hand, by means of an internal securing knob. The locking lever, if in locking position, with the vehicle door open, is automatically moved out of its locking position on closing the door. This automatic movement to an unlocked position can be negated by at least partially actuating the external operator and holding it in partially actuated position during closing movement of the door.

A considerable number of door latch mechanisms with this type of construction and method of functioning are already known. In most cases, in this application, an intermediate lever is arranged between the ratchet plate and the locking lever. This intermediate lever is adapted to be pivoted to a position so that when the external operating device is actuated it can transmit no movement to the locking lever so as to bring the latter out of its locked position upon movement of the ratchet plate. Because of this additional intermediate lever and the manner in which it is mounted and connected with the locking lever, the construction of these known door latch mechanisms is comparatively expensive and the method of functioning because of the full depression of the external operating means required to move the transmitting or intermediate lever to a nontransmitting position and the risk of rattling the associated parts, is not completely satisfactory.

It is an objective of the present invention to abolish the disadvantages of the known door latch mechanisms and to provide a door latch mechanism of the above-mentioned type of simple construction and satisfactory functioning.

SUMMARY OF THE INVENTION In accordance with the present invention this objective is achieved in that the locking lever, when set in pawl-blocking position with the door open, and thus with the latch element and ratchet plate situated in unlatched position, is moved positively out of its locked position by force transmitted from the ratchet plate to the locking lever through a toggle spring. The toggle spring is arranged with one arm rotatable in an aperture in the ratchet plate and its other arm in an aperture in the locking lever which is enlarged to permit a degree of free or lost motion. The movement of the ratchet plate occurs, as will be understood, as the latch element is moved from unlatched to latched position in closing the door.

The locking lever when set in pawl-blocking position with the door open and thus with the latch element and ratchet plate in unlatched position, is capable of being held secure in its blocking position during closing movement of the door. It is only necessary to gently or partially actuate the external operating device to negate the locking lever restoring movement. This is achieved by partial actuation of the external operator causing an abutment on the pawl means to engage a part of the locking lever to hold the same with sufficient resistence to negate the transfer of restoring force from the ratchet plate to the locking lever through the toggle spring.

DESCRIPTION OF THE DRAWING Further features and advantages of the present invention will be explained in greater detail making reference to the description, which now follows, reference being had to the drawing, in which:

FIG. 1 is a diagrammatic view in part sectional of a door latch mechanism in accordance with the present invention, as seen from a free-edge wall of a vehicle door, i.e., in the direction of the arrows l-l of FIG. 2; and

FIG. 2 is a diagrammatic view in part sectional taken substantially on the line 2-2 of FIG. 1.

DESCRIPTION OF THE INVENTION Referring now to the drawing, the latch mechanism, generally designated 11 has main plate 12 and a flange plate 13. The main plate 12 has rotatably journaled thereon a shaft or spindle 14 which carries on its outboard end a latch element 15 and on its inboard end a pawl wheel or ratchet plate 16. The latch element 15 and ratchet plate 16 are fixably coupled to a shaft 14 which is journaled in a bearing 17 arranged on the latch plate 12 so as to project at a right angle to the free-edge wall of the vehicle door (not shown).

A pawl 18 is pivotally carried on a pivot pin 19 fixed in the latch plate 12 and has, in a known manner, a hooklike projection 21 which is adapted to engage with abutments 22 or 23 so as to prevent rotation of the ratchet plate 16, the shaft 14 and the latch element 15. The cooperating ratchet and pawl are held in engagement by a tension spring 24. One end 25 of the spring 24 is coupled to the ratchet plate 16 and the other end 26 to the pawl 18. The spring 24 extends on a line between the pivot axes of the ratchet plate 16 and pawl 18 and tends to cause the two parts to rotate in mutually opposite directions.

The pawl 18 can be moved out of engagement with the ratchet plate 16 by a release lever 27 pivotal about the pivot pin 19. The pawl has an abutment 28 underlying an extension 29 of the release lever 27 so that when the latter is pivoted in a counterclockwise direction, as viewed in FIG. 1, the pawl is also pivoted in a counterclockwise direction away from the ratchet plate. The release lever 27 is operable in a known manner by an actuating member (not shown) coupled to the lever at the aperture 31 and to an external operator conventionally mounted on the exterior panel of a vehicle door. An inner operating device comprising a bellcrank lever 32 having an arm 33 (see FIG. 2) engageable with the pawl end 34 in a known manner may be provided to swing the pawl independently of the external operator.

When the pawl 18 is moved through actuation of the release lever 27, out of the position labeled closed in FIG. 1 to the position labeled open, the tension spring 24 pivots the ratchet plate 16, the shaft 14 and thus the latch element 15 in a direction such as to disengage the latch device from the striker pin (not shown) on a door jamb. A locking lever 35 is pivoted about a pin 36 carried on the latch plate 12. The axis of pivotal movement of the locking lever 35 is parallel to the axis of pivotal movement of the ratchet plate 16. The locking lever 35 cooperates with the release lever 27 by means of a projection 37 in such a manner that, with the locking lever 35 set in a locked" position, the projection 37 prevents any actuation of the pawl 18. The locking lever 37 is adapted to be pivotally moved by a force exerted at its one end 33 from the outside of the vehicle door by a conventional key-operated lock cylinder and at its other end 39 from the inside of the vehicle door by means of a bellcrank lever 41 having an interlocking connection at 42 (see FIG. 2) with the end 39 of the locking lever. The bellcrank lever 42 is coupled to a knob (not shown) accessible at the inner door window frame for moving the locking lever out of its "free" position in which it does not prevent movement of the pawl 18 into its locked" position in which it prevents disengagement of the pawl 18 from the ratchet plate 16.

The locking lever 35 is coupled to the ratchet plate 16 by way ofa toggle spring 43 one arm 44 of which is pivoted in the ratchet plate while the other arm 45 of which is permitted a degree of movement in an enlarged aperture 46 in the plate 12.

The coupling of the locking lever 35 to the ratchet plate 16 through the toggle spring 43 results in the following:

If, with the vehicle door open and thus with the latch element l5 and the ratchet plate 16 in the unlatched door open position, the locking lever 35 is moved to its locked" position and the door is thereupon closed, without the external operating mechanism having been actuated to cause the latter to exert force on the pawl 18, then a portion of the torque acting on the ratchet plate 16 on the closing of the door is transmitted by way of the toggle spring 43 to the locking lever 35. This spring-transmitted force moves locking lever 35 out of its locked" position into its free" position.

If, with the door open and thus with rotary latch element and ratchet plate 16 situated in the open position, the locking lever 35 is moved into a locked position and the door is thereupon closed at the same time the external operating mechanism which acts on the pawl 18 is slightly depressed, a tang 47 on the projection 37 on the locking lever 35 prevents movement of the latter into its free" position by the rotation of the latch element 15 and the ratchet plate 16 through the toggle spring 43.

The toggle spring 43 obviously must be designed as to its force and its disposition so that with the rotational movement occurring at the ratchet plate 16 in closing the door, it exerts a sufficiently high leverage on the locking lever 35, even under unfavorable conditions, to urge the latter in the direction of the free condition. The force of the toggle spring 43, however, is rendered ineffective by the general depression of the external operating mechanism. This general depression results in the release lever 27 being held in the position to block through the tang 47 the locking lever 35 from being moved from its locked" position. In this manner the vehicle door can be locked without the necessity of using a key in the keycylinder-locking device.

The mechanism provides an incidental advantage in that with the door open and the locking lever 35 situated in the free position, the external operating mechanism can be moved to a full-open position. With the locking" lever set in the locked position, the external operating mechanism can be moved only a small extent toward full-open position, i.e. by the amount corresponding to the clearance between release lever 27 and the projection 37 of the locking lever 35. Thus, it can be ascertained almost at once by a light actuation touch on the external operating mechanism whether the locking lever has been set in locked position or not.

It will be understood that this invention is not to be limited to the exact construction shown and described but that various changes and modifications may be made without departing from the spirit and scope ofthe invention as defined in the appended claims.

We claim:

1. In a door latch mechanism comprising:

a latch plate,

a shaft supported in bearing means on said latch plate and having a latch element fixedly coupled thereto on the outboard side of said plate and a ratchet plate fixedly coupled thereto on the inboard side of the plate,

a pawl means pivotally supported on the inboard side of said latch plate for swinging movement about a pivot axis parallel to the axis of said shaft and engageable with the ratchet plate to hold the latter in latched condition,

a tension spring extending between said pawl and ratchet plate urging the two in mutually opposed directions into engagement with each other,

external and internal operators coupled to said pawl means for moving the latter into ratchet-plate-disengaged position,

a locking lever pivotally mounted on the inboard side of said latch plate having a part thereof positionable to block movement of said pawl means in ratchet-plate-disengagin direction,

said ocking lever being operable by external and internally operable lever actuators,

and restoring means coupling said locking lever to the ratchet plate, I

said restoring means being effective upon said locking lever being placed in pawl movement locking position with the latch element in unlatched position to restore the locking lever to nonblocking position,

characterized in that the restoring means coupling the locking lever to the ratchet plate comprises a toggle spring having one arm pivoted in an aperture in the ratchet plate and a second arm pivoted in an aperture in the locking lever,

said last-mentioned aperture being enlarged to provide a degree of free movement of said second arm relative thereto,

said toggle spring being effective to transmit ratchet plate torque to the locking lever to move the latter from pawlmeans-locking position to pawl-means-nonblocking positron.

2. In a door latch mechanism according to claim 1 in which:

the restoring means for restoring the locking lever from pawl-means-blocking position to nonblocking position with the latch device and ratchet plate in unlatched position can be rendered ineffective,

characterized in that the locking lever and pawl means have abutting portions which are engageable upon at least partial actuation of the external operator,

the engagement of said abutting portions resisting the force exerted by the toggle spring tending to urge the locking lever to nonblocking position upon rotation of the latch elements and the ratchet plate from unlatched to latched condition. 

1. In a door latch mechanism comprising: a latch plate, a shaft supported in bearing means on said latch plate and having a latch element fixedly coupled thereto on the outboard side of said plate and a ratchet plate fixedly coupled thereto on the inboard side of the plate, a pawl means pivotally supported on the inboard side of said latch plate for swinging movement about a pivot axis parallel to the axis of said shaft and engageable with the ratchet plate to hold the latter in latched condition, a tension spring extending between said pawl and ratchet plate urging the two in mutually opposed directions into engagement with each other, external and internal operators coupled to said pawl means for moving the latter into ratchet-plate-disengaged position, a locking lever pivotally mounted on the inboard side of said latch plate having a part thereof positionable to block movement of said pawl means in ratchet-plate-disengaging direction, said locking lever being operable by external and internally operable lever actuators, and restoring means coupling said locking lever to the ratchet plate, said restoring means being effective upon said locking lever being placed in pawl movement locking position with the latch element in unlatched position to restore the locking lever to nonblocking position, characterized in that the restoring means coupling the locking lever to the ratchet plate comprises a toggle spring having one arm pivoted in an aperture in the ratchet plate and a second arm pivoted in an aperture in the locking lever, said last-mentioned aperture being enlarged to provide a degree of free movement of said second arm relative thereto, said toggle spring being effective to transmit ratchet plate torque to the locking lever to move the latter from pawl-meanslocking position to pawl-means-nonblocking position.
 2. In a door latch mechanism according to claim 1 in which: the restoring means for restoring the locking lever from pawl-means-blocking position to nonblocking position with the latch device and ratchet plate in unlatched position can be rendered ineffective, characterized in that the locking lever and pawl means have abutting portions which are engageable upon at least partial actuation of the external operator, the engagement of said abutting portions resisting the force exerted by the toggle spring tending to urge the locking lever to nonblocking position upon rotation of the latch elements and the ratchet plate from unlatched to latched condition. 